A pulsed periodically poled lithium niobate optical parametric oscillator operating in a cavity with a grazing-incidence grating configuration was used for sensitive and precise measurement of trace quantities of methane in nitrogen by photoacoustic spectroscopy with a novel differential photoacoustic detector. A sensitivity of 1.2 parts in 109 by volume of methane was obtained in direct calibration measurements (not extrapolated). With this apparatus, in situ measurement of the methane concentration in ambient air under atmospheric conditions was demonstrated.
© 2002 Optical Society of America
Original Manuscript: August 3, 2001
Revised Manuscript: December 20, 2001
Published: May 20, 2002
András Miklós, Chin-How Lim, Wei-Wei Hsiang, Geng-Chiau Liang, A. H. Kung, Andreas Schmohl, and Peter Hess, "Photoacoustic measurement of methane concentrations with a compact pulsed optical parametric oscillator," Appl. Opt. 41, 2985-2993 (2002)